1. Field of the Invention
The present invention relates to an apparatus and a method for Automatic Repeat reQuest (ARQ) in a wireless communication system. More particularly, the present invention relates to an apparatus and a method for transmitting ACKnowledge (ACK) channels for ARQ in a wireless relay communication system.
2. Description of the Related Art
Wireless communications systems are subject to error in transmission data depending on a status of a radio channel. To control and recover the data error, the wireless communications systems employ an Automatic Repeat reQuest (ARQ) scheme or a Forward Error Correction (FEC) scheme. Herein, according to the ARQ scheme, a receiver requests a transmitter to retransmit the corrupted data. According to the FEC scheme, the receiver corrects the data error.
Using the ARQ scheme, the receiver sends error information of a packet received from the transmitter, to the transmitter. That is, when the received packet is free from error, the receiver sends an Acknowledge (ACK) signal to the transmitter. In contrast, when the received packet is corrupted, the receiver sends a Negative ACK (NACK) signal to the transmitter.
When receiving the ACK signal from the receiver, the transmitter transmits a new packet. When receiving the NACK signal from the receiver, the transmitter retransmits the data to the receiver in response to the NACK signal.
The wireless communications systems provide a relay service using a Relay Station (RS) in order to provide a better radio channel to a Mobile Station (MS) traveling in a cell boundary or in a shadow area. More specifically, the wireless relay communication system can provide a better radio channel between a Base Station (BS) and the MS by relaying data transmitted and received between the BS and the MS via the RS.
The BS, the RS, and the MS in the wireless relay communication system transmit and receive data over radio channels. In this respect, what is needed is an ARQ method for controlling and recovering data error in consideration of the RS in the wireless relay communication system.